Gripper with dual-insert body

ABSTRACT

In order to reduce or to prevent wear on the tufting gripper ( 16 ) at the contact point with the tufting needle ( 18 ), an additional insert  28  is provided in addition to a wear-resistant cutting insert ( 27 ), said additional insert ( 28 ) being directed at interacting with the tufting needle ( 18 ). Said additional insert consists of a material that, paired with the tufting needle ( 18 ), forms an optimal sliding combination. Preferably, the additional insert ( 28 ) is a soft needle-saving insert. Preferably, the cutting insert ( 27 ) is a hard wear-resistant insert. The two inserts ( 27, 28 ) may be accommodated separately in different pockets ( 36, 37 ) or together in one pocket ( 31 ). They may be connected with each other or be made in one piece.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the priority of European Patent Application No. 10 171 112.5, filed Jul. 28 2010, the subject matter of which, in its entirety, is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention relates to a tufting gripper for a tufting machine, in particular for the manufacture of goods with cut pile.

Goods that are provided with cut pile, for example carpets, are typically produced on tufting machines that comprise a gripper arrangement with a plurality of grippers. The grippers are associated with cutting knives. This arrangement has been known, for example, from publication EP 1 826 306 A1. As can be seen, in that publication the grippers interact with needles of a sinker that punch the pile thread through a backing material. The resultant loops are picked up by grippers that are provided with a cutting edge. Each gripper is associated with a cutting knife that is disposed to cut the loops picked up by the respective gripper.

Publication EP 1 826 307 A1 also discloses a similar arrangement. Also in this case each of the grippers has a base body that works as a counter knife element for the cutting knives and has an appropriate cutting edge.

Furthermore, it has been known to design the cutting edge to be provided on the gripper with an insert of hard metal, said insert being inserted in a pocket of the gripper body. Regarding this, reference is made, for example, to EP 1 953 290. This publication suggests that the body of hard metal be secured in a form-fitting manner in the pocket by plastic deformation of the pocket edge. In doing so, a certain disengagement of the insert of hard metal from the flexible lateral deformations of the gripper body is achieved.

When the tufting arrangement is being operated, the grippers that are disposed to pick up the pile thread loops sweep along the tufting needles. This can result in damage to the tufting needles. For example, while the eye of the tufting needle sweeps long the hard-metal insert of the gripper, sharp edges may form on the eye and, as a result of this, individual filaments of the pile thread can be damaged. Also, damage to the tufting grippers at the contact points between the gripper body and the needle cannot be precluded.

Considering this, it is the object of the invention to suggest a concept with which the service life of the tufting device can be improved.

SUMMARY OF THE INVENTION

The above object generally is achieved with the tufting gripper in accordance with the invention that comprises a gripper body that is provided with a cutting insert having a surface of a hard material, as well as with an additional insert that has a surface that is different from the surface of hard material. The cutting insert having the hard-material surface is preferably a straight, curved, convoluted, stepped or cogged cutting edge and is preferably placed on the gripper body in such a manner that it interacts with the associate cutting knife. Preferably, the cutting insert is a rigid body such as, for example, a hard-metal body, a ceramic body, a steel body provided with a hard-material layer, another type of body or the like. In this case, the cutting insert is inserted in an appropriate pocket, i.e., a recess of the gripper body, and secured in said pocket. Alternatively, the cutting insert may also be designed entirely in one piece with the gripper body; however, also in this case, said cutting insert defines the hard-material surface, for example, in the form of a coated region of the gripper body. The hard-material surface may be the surface of a hard-metal insert, for example, a tungsten carbide surface, the surface of a ceramic insert, or another layer applied to the respective base body by PVD or DVD process or coated by means of another method, such layers being, for example, a DLC layer, TiN layer, TiC layer, AL₂O₃ layer or the like. In view of the material of the cutting knife and the pile thread to be cut, such a layer is designed so as to display the highest possible wear resistance.

The additional insert in accordance with the invention has a different surface and is preferably positioned at the point of the gripper body that comes into contact with the tufting needle. Preferably, this insert has a surface that does not damage the tufting needle when the tufting needle and said additional insert come into contact with each other. In particular, the surface may display good sliding properties. For example, the additional insert may consist of a soft metal or non-metal, for example, a ceramic material displaying a low coefficient of friction, or of a metal having a coating that ensures a low coefficient of friction and a low abrasion effect between the surface of the insert and the tufting needle. For example, the surface may be a carbon-nitride coating or a ceramic coating. This coating may also be applied directly to the gripper body so that the additional insert and the gripper body can ultimately be viewed as being a one-piece component.

Both the cutting insert and the additional cutting insert have to be arranged in a pocket of the gripper body and be secured in said pocket. For securing purposes, the respective cutting insert, as well as any other insert, must be in form-fitting and/or material-bonding connection with the gripper body. Preferably, the cutting insert and/or the other insert are joined to the gripper body by soldering, gluing, welding (e.g., by welding spots or seams provided on the pocket edge) and/or are secured in place by a plastic deformation of the pocket edge of the pocket that accommodates the respective insert. In addition, one or more spring means may be provided on the gripper body, said spring means displacing the cutting insert and/or other insert into their desired positions, preferably toward the gripper tip, and thus secure said cutting inserts in the desired positions. This can be aided by a material-bonding connection between the respective insert and the gripper body, for example, by using a hard solder or any other, e.g., flexible, connecting material. The spring means provided on the gripper body then mainly becomes active when the insert is in correct positional arrangement.

The two inserts (cutting insert and additional insert) may be accommodated in separate pockets or also in a shared pocket. The pocket may be configured as a cutout on the gripper body and thus be open toward both flat sides of the gripper body. The two inserts may be arranged so as to lie flat on top of each other in this cutout or pocket and be connected with the gripper body. The two inserts may also be connected with each other, for example, by material-boding. They may be soldered, glued or welded to each other. They consist of different materials or have at least different surfaces. They may consist of the same base material and be only provided with different coatings on the two sides that face away from each other. It is also possible to provide the two coatings on a single carrier body.

When the cutting insert and the additional insert are connected or combined with each other in accordance with at least one of the aforementioned methods, a combined unit is being formed, said unit having a hard-material surface as well as a surface different from the hard-material surface. The combined insert can be connected with the gripper body in any of the previously described ways.

In order to achieve a material-bonding connection displaying controlled quality, it is desirable to maintain a prespecified joint thickness at the joint, said joint being filled with glue or hard solder (or another joining material). To do so, spacer means may be provided on the respective insert (cutting insert and/or any other insert and/or combined unit). Such spacer means are, for example, projections placed on one or more suitable points of the circumference of the insert, for example, small ribs or knobs that are higher than the edge of the insert. In doing so, the height of the respective projection corresponds to the desired thickness of the joint.

Additional details of advantageous embodiments of the invention are the subject matter of the drawings, the description or the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a tufting system comprising a tufting gripper, tufting needle and tufting knife.

FIG. 2 is a perspective view of the tufting gripper as in FIG. 1.

FIG. 3 is another perspective view of the tufting gripper as in FIGS. 1 and 2.

FIG. 4 is a representation of a detail, in section along line IV-IV, of the tufting gripper as in FIG. 3.

FIG. 5 is a view corresponding to FIG. 4, vertically in section, of a modified embodiment of the tufting gripper modeled after the gripper as in FIGS. 1 through 3.

FIG. 6 is a sectional view corresponding to FIG. 4 or FIG. 5, of a further modified embodiment of the tufting gripper.

FIG. 7 is a side view of an insert for the tufting gripper as in FIGS. 1 through 4.

FIG. 8 is an alternative embodiment of a tufting gripper in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a tufting device 10 that is used for the manufacture of tufted goods 11. Such goods are, for example, cut pile carpets. This includes a flat, planar, e.g., textile, backing material 12 as indicated in dashed lines in FIG. 1.

This backing material is provided with a pile thread 13 that is punched through the backing material 12 in order to first form the loops 14. As the process continues, these are cut open in order to form open loops and thus form cut pile 15. This is accomplished with a tufting gripper 16 that is associated with a cutting knife 17. Numerous tufting grippers 16 are arranged next to each other on a sinker that imparts the tufting grippers 16 with the desired working motion. A corresponding number of cutting knives 17 is also arranged on a sinker that, for the cutting operation, performs a movement directed against the grippers 16.

In order to produce the loops 14 to be picked up by the gripper 16, i.e., for punching the pile thread 13 through the backing material 12, tufting needles 18 are used, each of said needles having its own pile thread 13 moving through its eye. The tufting needles 18 and the cutting knives 17 have a design that has been known per se. The tufting gripper 16 may be inserted like a conventionally designed tufting gripper; however, the gripper has been modified in accordance with the invention in order to improve service life, in particular the service life of the tufting needles 18:

The tufting gripper 16 in accordance with the invention comprises a gripper body 19 as is shown, in particular, by FIGS. 2 and 3. The gripper body 19 is configured so as to represent a flat component and has two flat sides 20, 21. These are not necessarily plane, however, they may have plane regions. The flat sides 20, 21 of adjacent grippers 16 define between them narrow, slit-like passages for the legs of the loops 14 and the cut pile 15, as well as for the tufting needles 18 and the cutting knives 17. In particular when dense pile is concerned, these passages are relatively tight. By definition, the tufting needles 18 thus contact the grippers 16. Likewise, the cutting knives 17 contact the grippers 16, at least while the loops 14 are being cut.

As shown by FIG. 1, the body 19 of the gripper 16 comprises an elongated gripping finger 22 extending toward the tufting needle 18, as well as a base section 24. On its free end, the gripping finger 22 may have a catch 23 that is bent away from the backing material 12, said catch forming a hook. The finger 22 is straight between the catch 23 and the base section 24 of the body 19 of the gripper 16. As is shown by FIG. 1, the finger 22 is disposed to pick up the loops 14. To do so, said finger has a straight edge 25 on its lower side. This edge acts as the cutting edge 26, i.e., at least on one side of the gripper body 19.

The cutting edge 26 is provided on one cutting insert 27 and, at least in the present exemplary embodiment, extends—however not necessarily—along the entire length of the finger 22 from the base section 24 to the catch 23. Arranged adjacent to the cutting insert 27 is an additional insert 28 which, in the present exemplary embodiment, has the same contour as the cutting insert 27 and abuts against said insert at a plane surface 29. While the cutting insert 27 adjoins the flat side 21 of the tufting gripper 16 (FIG. 3), the other insert 28 adjoins the flat side 20 without steps and offsets (FIG. 2).

The cutting insert 27 and the additional insert 28 are connected to each other at the plane surface 29, for example, by glue or solder, and thus form a unit 30, as is obvious from FIG. 4, in particular. Other joining techniques such as, e.g., using laser spots or laser seams at the edge of the surface 29 can be employed.

The unit 30 and thus also the cutting insert 27, as well as the additional insert 28, are positioned in a pocket 31 that is formed in the gripper body 19 and extends from the base section 24 to the catch 23. As is obvious from FIGS. 2 and 3, the pocket 31 is open toward both flat sides 20, 21 of the gripper body 19. The unit 30 consisting of the two inserts 27, 28 can be secured by material boding. For example, solder may be used for material-bonded securing, said solder being used to solder the unit 30 to the gripper body 19, i.e., along the edge of the pocket 31.

The cutting insert 27 has a hard-material surface 32. If the cutting insert 27 consists of a hard material, the surface 32 may be a surface consisting of such a material, for example. Such a material can be hardened steel, hard metal such as, for example, tungsten carbide, a cermet or also a ceramic. It is also possible to make the cutting insert 27 of a first hard material and the hard-material surface 32 of a second hard material. For example, the cutting insert 27 may consist of tungsten carbide and the hard-material surface 32 may consist of titanium nitride, aluminum oxide, another hard material or of a layer assembly consisting of various hard materials.

The hard-material surface 32 extends at least up to the cutting edge 26 and, preferably, circumscribes said cutting edge up to a narrow underside 33 of the cutting insert 27 (FIG. 4).

Preferably, the additional insert 28 consists of another material than the cutting insert 27. Preferably, this is a material having a low coefficient of friction. Adjoining the flat side 20, the insert 28 has a surface 34 that is distinctly different from the hard-material surface 32. In particular the surface 34 exhibits a low abrasion effect in view of the contact with the tufting needle 18. For example, the additional insert 28 may consist of a material displaying emergency lubrication properties, for example a carbon-containing metal structure, a tin-containing metal structure or the like. Also, the surface 34 may be a ceramic surface having a low coefficient of friction and the most minimal roughness height.

Briefly, the tufting device 10 described so far operates as follows:

During operation, the plurality of tufting needles 18 held on a sinker punch the pile thread 13 through the backing material 12 and to form loops. These loops are grasped by the plurality of tufting grippers 16 supported by the sinker due to a relative movement of said gripers, so that the loops 14 can be picked up by the fingers 22, as is obvious from FIG. 1. During the operating cycle, the plurality of knives 17 held on a sinker bar push in the direction of the picked-up loops 14 and separate them on the cutting edges 26 of the plurality of tufting grippers 16, so that the cut pile 15 is formed.

During this process, the cutting knives 17 contact the cutting insert 27 and slide along the hard-material surface 32 of said insert. The wear is minimal.

The tufting needles 18 come into contact with the tufting grippers 16. In particular, in doing so, the tufting needles 18 slide along the additional insert 28. The minimal abrasion effect of the insert 28 that could result, for example, due to the hardness and/or smoothness and/or softness and/or emergency lubrication property of said insert, the wear of the needles is negligibly small. In particular a partial sharpening of the needle eye edges is prevented which, otherwise could lead to damage to the pile thread 13.

Numerous modifications of the tufting gripper 16 are possible. As is shown by FIG. 5, for example, the cutting insert 27 and the additional insert 28 can be configured as separate inserts. In this case, the pocket 31 does not extend through the entire thickness of the tufting gripper 16. Rather, said pocket has a bottom 35 that divides the pocket 31 into two individual pockets 36, 37. The pockets 36, 37 may have the same contour or different contours. They are open toward different sides. While the individual pocket 36 borders the flat side 21, the individual pocket 37 borders the flat side 20. Also, considering this exemplary embodiment, the cutting insert 27 and the additional insert 28 can be fastened in the pockets 36, 37 by material-bonding, for example, by gluing or soldering.

Furthermore, as is shown by FIG. 6, the combined unit 30 comprising both inserts 27, 28 can be based on a shared base body 38. Said base body may be provided, on one side, with a thin plate or also with a layer 39 that represents the hard-material surface 32. The hard-material surface 32, in turn, adjoins the flat side 21 in a manner without offset and without gaps. The surface 34 located on the other side of the tufting gripper 16 preferably consists of a different material that may be applied in the form of a thin layer or a plate 40 to the base body 38. This plate or layer 40—in the form of the lateral surface 34—then creates a sliding surface for the tufting needle 18, in particular. Each of the previously mentioned connecting techniques may be used for fastening the unit 30 in accordance with FIG. 6 in the pocket 31. The cutting insert 27, the additional insert 28 and/or the unit 30 in accordance with FIG. 4 or 6 may have the side view in accordance with FIG. 7. The external circumference of the respective insert that is facing the wall of the pocket 31 (36 or 37) may be provided with spacer means 41. Such spacer means are, for example, knob-like or rib-like projections 42, 43 having a height corresponding to the thickness of the desired joint that is formed between the circumference of the unit 30 and the edge of the pocket 31. Preferably, this height is a few tenths of a millimeter. It is disposed, for example, to produce a hard solder joint of defined thickness and also to position the respective insert 27 or the respective unit 30 in an extremely precise manner in the pocket 31.

FIG. 8 illustrates another embodiment of the invention represented by the form of the tufting gripper 44. This gripper comprises an elongated finger 22. For example, the catch 23 may be omitted. It is assumed that the cutting insert 27 and the additional insert 28 are arranged as a combined unit in the pocket 31. On its tip end, the pocket 31 has a form-fitting structure 45, said structure securing the unit 30 in the pocket 31 when the unit 30 is pushed against said form-fitting structure 45. For example, the edge of the pocket 31 has an arcuate form on its tip-side end. The edge of the pocket 31 circumscribes the insert or the unit 30 in a hook-like manner, thus securing said insert in a form-fitting manner in vertical direction. The edge of the pocket 31 may be straight, relative to the transverse direction, from the flat side 20 to the flat side 21. Alternatively, the form-fitting structure 45 may have a shape that is rounded or angled in a direction transverse to the tufting gripper 45 in order to also secure the lateral position of the unit 30 in a form-fitting manner.

A spring means 46 is arranged on the opposite end of the pocket 31, said spring means biasing the unit 30 with respect to the form-fitting structure 45. The spring means 46, for example, is a released spring tab 47 provided on the body of the tufting gripper 44. As a result of the spring force is applied by the spring means 46 the unit 30 is positioned in a spring-actuated, non-positive, manner. As a result of this, the gap at the transition from the body 19 of the tufting gripper 44 to the insert or the unit 30 is as small as possible. When the unit 30 is connected with the tufting gripper 44 in a material-bonded manner, an exact positioning of the insert or the unit 30 is accomplished. This position is decisive for the quality of the resultant transition between the lateral surfaces of the insert or the unit 30 and the flat sides of the tufting gripper 44. Due to the precise non-positive fixation of the unit 30 during the soldering operation, laterally impinging forces when the solder solidifies or the glue hardens do not have a negative influence on fastening.

In all the aforementioned embodiments, this way of securing the insert by spring force due to a spring means 46 may be separately applied to the unit 30 as well as to the cutting insert 27 and the additional insert 28, i.e., to embodiments comprising spacer means 41 as well as to embodiments without spacer means 41.

In order to reduce or to prevent wear on the tufting gripper 16 at the contact point with the tufting needle 18, an additional insert 28 is provided in addition to a wear-resistant cutting insert 27, said additional insert 28 being directed at interacting with the tufting needle 18. Said additional insert consists of a material that, paired with the tufting needle 18, forms an optimal sliding combination.

Preferably, the additional insert 28 is a soft needle-saving insert. Preferably, the cutting insert 27 is a hard wear-resistant insert. The two inserts 27, 28 may be accommodated separately in different pockets 36, 37 or together in one pocket 31. They may be connected with each other or be made in one piece.

It will be appreciated that the above description of the present invention is susceptible to various modifications, changes and modifications, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

LIST OF REFERENCE NUMERALS

-   10 Tufting device -   11 Goods -   12 Backing material -   13 Pile thread -   14 Loops -   15 Cut pile -   16 Tufting gripper -   17 Cutting knife -   18 Tufting needle -   19 Body of 16 -   20 Flat side -   21 Flat side -   22 Gripping finger -   23 Catch -   24 Base section of 19 -   25 Lower edge of finger 22 -   26 Cutting edge of the cutting insert 27 -   27 Cutting insert -   28 Additional insert -   29 Plane surface between the inserts 27, 28 -   30 Unit comprising the cutting insert 27 and the additional insert     28 -   31 Pocket -   32 Hard-material surface of the cutting insert 27 -   33 Narrow side of the cutting insert 27 -   34 Lateral surface of the additional insert 28 -   35 Bottom of the pockets 36, 37 -   36 Individual pocket for the cutting insert 27 -   37 Individual pocket for the additional insert 28 -   38 Common base body for the inserts 27, 28 -   39 Plate or layer with hard-material surface 32 -   40 Plate or layer with sliding surface -   41 spacer means -   42 Knobs -   43 Knobs -   44 Tufting gripper -   45 Form-fitting structure -   46 Spring means -   47 Spring tab 

1. Tufting gripper (16, 44) for a tufting machine, comprising: a gripper body (19); a cutting insert (27) having a hard-material surface (32); and, an additional insert (28) having a surface (34), said surface being different from the hard-material surface (32).
 2. Tufting gripper as in claim 1, characterized in that the cutting insert (27) has a cutting edge (26).
 3. Tufting gripper as in claim 1, characterized in that the cutting insert (27) is inserted and secured in a pocket (31, 36) of the gripper body (19).
 4. Tufting gripper as in claim 1, characterized in that the additional insert (28) has a surface (34), said surface consisting of a material displaying different sliding properties than the hard-material surface (32) of the cutting insert (27).
 5. Tufting gripper as in claim 1, characterized in that the additional insert (28) is inserted and secured in a pocket (31, 37) of the gripper body (19).
 6. Tufting gripper as in claim 1, characterized in that the cutting insert (27) and the additional insert (28) are firmly connected with each other and form a combined unit (30), said unit being provided with the hard-material surface (32) and the surface (34) that is different from the hard-material surface (32).
 7. Tufting gripper as in claim 1, characterized in that the cutting insert (27) is arranged on one side (21) of the gripper body (19) and the other insert (28) is arranged on the other side (20) of the gripper body (19).
 8. Tufting gripper as in claim 1, characterized in that the cutting insert (27) and/or the additional insert (28) are connected with the gripper body (19) in a material-bonding manner.
 9. Tufting gripper as in claim 8, characterized in that spacer means (41) are provided on the cutting insert (27) and/or on the additional insert (28) in order to ensure a minimum joint thickness for the material-bonding connection. 